Does it still hold true what Rob wrote there? That
not support the deletion of users? Is that still the case in 1.11.0?
Or does someone know of an extension which will allow to easily
remove user accounts?
It still applies for the same reasons. What are you meant to do with
article histories of articles the deleted user edited? A user with no
(undeleted) edits can generally be deleted if you really have to (by
altering the database manually), but there's rarely any need - you can
always rename the user to "DeletedUser1".